Occupant sensor seat switch

ABSTRACT

A pressure sensitive occupant sensor seat switch to detect the presence of an occupant in an automobile seat. A flat body formed of electrically insulating, resilient compressible material has one or more openings extending therethrough. A pad formed of electrically nonconductive compressible, resilient, inorganic or semiorganic material having discrete electrically conductive particles dispersed throughout occupies each opening. When the pad is uncompressed, the electrically conductive particles do not engage one another. When the pad is compressed, however, the electrically conductive particles engage one another and the pad becomes conductive. Electrical conductors on both sides of the insulating body make electrical contact to the pads so that the switch assembly controls a device connected to it when pressure is applied.

United States Patent [191 Blinkilde et al.

[ OCCUPANT SENSOR SEAT SWITCH [75] Inventors: Paul J. Blinkilde, LathrupVillage;

Floyd J. Sandi, Clawson, both of Mich.

[73] Assignee: Essex International, Inc., Fort Wayne, Ind.

[22] Filed: Feb. 26, 1973 [21] Appl. N0.: 335,786

[52] U.S. Cl. 200/85 A, 340/278 [51] Int. Cl. H0111 3/14 [58] Field ofSearch 200/85 A, 86 R, 166 C; 338/114, 100; 340/278 [56] ReferencesCited UNITED STATES PATENTS 2,044,080 6/1936 Kemper 200/86 R 3,290,75612/1966 Dreyer 317/101 CM 3,509,296 4/1970 Harshman et al 200/86 R3,648,002 3/1972 DuRocher 200/166 C 3,654,407 4/1972 Kepner 200/86 R3,704,352 11/1972 Fontaine 200/85 A 3,718,791 2/1973 Szablowski 200/85 AJan.7, 1975 Primary Examiner-David Smith, Jr. Attorney, Agent, orFirm-Robert D. Sommer [57] ABSTRACT A pressure sensitive occupant sensorseat switch to detect the presence of an occupant in an automobile seat.A flat body formed of electrically insulating, resilient compressiblematerial has one or more openings extending therethrough. A pad formedof electrically nonconductive compressible, resilient, inorganic orsemiorganic material having discrete electrically conductive particlesdispersed throughout occupies each opening. When the pad isuncompressed, the electrically conductive particles do not engage oneanother. When the pad is compressed, however, the electricallyconductive particles engage one another and the pad becomes conductive.Electrical conductors on both sides of the insulating body makeelectrical contact to the pads so that the switch assembly controls adevice connected to it when pressure is applied.

4 Claims, 11 Drawing Figures Patented Jan. 7, 1975 3,859,485

3 SheetsSheet 1 Patented Jan. 7, 1975 3 Sheets-Sheet 2 mQ-E PatentedJan. 7, 1975 3 Sheets-Sheet 5 Qu y-h- 1 OCCUPANT SENSOR SEAT SWITCHBACKGROUND OF THE INVENTION With the advent of certain Federalrequirements for safety systems in automobiles it has been necessary toprovide automobile seats with pressure sensitive switches to detect thepresence of an occupant. The requirements for models prior to 1974dictate the need for a driver and a passenger seat switch. However, anadditional switch is required on 1974 models to detect the presence ofan occupant in the middle of the front seat. Seat switches presentlyused do not function properly in the center front seat because they areinfluenced by the weight of the driver and/or right front passenger.

SUMMARY OF THE INVENTION Briefly, an occupant sensor seat switch isprovided which is placed in a pocket in the foam padding of aconventional automobile seat just below the seat covering. The switch iscomprised of a body formed of an electrically nonconductive,,compressible, resilient material such as polyurethane foam. One or moreopenings extend through the flat body and a pad formed of a resilient,compressible, nonconductive, organic or semiorganic material havingdiscrete electrically conductive particles dispersed throughout occupieseach such opening. The pads are conductive only when compressed and arenonconductive when in an uncompressed state. When a plurality of pads isemployed, electrical connections are made to the pads such that it isnecessary to compress at least two pads in order to complete a circuit.According to an alternate embodiment, the pads are connected in parallelsuch that it is necessary to compress only one pad to complete acircuit.

Accordingly, it is an object of this invention to provide a pressuresensitive switch that is substantially unaffected by a pressure unlessthat pressure is applied directly over the switch.

It is another object of the invention to provide a pressure sensitiveoccupant sensor seat switch to detect the presence of an occupant in anautomobile seat.

Another object of the invention is to provide a pressure sensitiveoccupant sensor seat switch to detect the presence of an occupant in anautomobile seat is unaffected by the presence of other occupants in theautomobile.

BRIEF DESCRIPTION OF THE DRAWINGS conductive particles dispersedthroughout;

FIG. 5 is a cross sectional view of the copper coated film used to makecontact to resilient pads;

FIG. 6 is an electrical schematic of the embodiment shown in FIG. 2;

FIG. 7 is a top plan view of a second embodiment of the invention;

FIG. 8 is a cross sectional view taken along lines 8-8 of FIG. 7;

FIG. 9 is a top plan view of a third embodiment of the invention;

FIG. 10 is a cross sectional view taken along lines 10-10 of FIG. 9; and

FIG. 11 is an electrical schematic of the embodiment shown in FIGS. 9and 10.

DESCRIPTION OF THE PREFERRED EMBODIMENT An occupant sensor seat switchconstructed in accordance with the invention comprises essentially aunitary body formed of a synthetic, resilient nonconductive substancesuch as silicone rubber or polyurethane, body having at least one inlayor portion thereof constituted by nonconductive material such assilicone rubber or polyurethane throughout which is dispersed a quantityof discrete, electrically conductive particles. According to theinvention the pad containing the conductive particles and the dispersionof the particles are such that, when the pad is in its normal,unstressed condition the electrical resistance of the pad is infiniteand the pad is nonconductive. When the pad is subjected to compressiveforce of sufficient magnitude, however, the particles are forced to moverelatively to one another into particle to particle engagement. Theresistance of the pad thereupon changes to that of the metal particlesand the pad becomes electrically conductive. Upon release of thecompressive force, the inherent resilience of pad restores it to itsnormal, unstressed condition whereupon the particles again moverelatively to one another, but in this instance in such manner as todisengage one another and render the pad nonconductive. The change fromconductive to nonconductive condition, and vice versa, occurs rapidly,as is the case with a conventional switch of the snap-action type.

The number of particles which move into particle-toparticle engagementmay vary according to the force applied to the body or to thecompressive force under which it is formed, and it is not essential thatall of the particles engage one another. It is only necessary that atrain of particles be in engagement between the other current conductorsof a circuit so as to establish a conductive path through the body. Infact, it is preferred that not all of the particles in the body engageone another. In such a case, one train of engaged particles may beconsumed by an overload current, thereby rendering the bodynonconductive. Other particles, however, will be unaffected therebymaking it possible for such other particles to form additional trainsfor current conduction.

An advantage of devices of the kind herein disclosed is the ease withwhich they may be varied to conform to differing operating requirements.In general, the compressive force required to render a pad conductivewill be directly proportional to the thickness of the pad. A givensample of the composite body or pad, therefore, can be made responsiveto extremely light pressures or responsive to relatively heavypressures, depending on the thickness of the pad. The sensitivity of thedevice also is related to the quantity and size of the conductiveparticles. The force required to render a pad conductive varies, ingeneral, inversely according to the quantity of particles containedwithin the pad and varies directly according to the size of suchparticles. It is possible, therefore, to manufacture devices havinggreatly differing operating characteristics.

The force required to render a composite body conductive and the amountof travel necessary to effect compression of the pad to a state ofconductivity also is related to the density of the body. Thus, arelatively dense body requires the application of a greater compressiveforce than does a less dense or foamedbody, whereas the foamed bodyrequires a greater compressive movement than does the more dense body.Consequently, the force, and stroke of an operating mechanism can varywithin wide limits.

The material from which the device is made should be resilient at bothlow and high temperatures, readily moldable, stable at hightemperatures, porous or nonporous, resistant to ozone, oil and arcing,in-organic, semiinorganic durable, low in carbon content, and have highdielectric strength. Certain kinds of polyurethanes and silicone rubberspossess all of these properties. Silicone rubbers are prepared bymilling together a dimethyl silicone polymer, an inorganic filler, and avulcanizer or catalyst. Many different fillers may be used, such astitania, zinc oxide, iron oxide, silica, and the like. The type andamount of filler used alters the chemical, physical, and electricalproperties. It is possible, therefore, to produce many different kindsof silicone rubbers which have the properties referred to above.

Many varieties of silicone rubbers exist which perform satisfactorily.For example, good results have been obtained with silicone rubbersformed by combining resins 850 or 3120 '(Dow Corning Corporation,Midland, Michigan) with'the manufacturers recommended S. For H Catalystorvulcanizer which includes as its active ingredients such compounds asdibutyl tin dilorate or stanis octoate. Satisfactory results also havebeen obtained with silicone rubbers formed by combining RTV-7 resin(General Electric Company, Schenectady, New York) with the manufacturersNuocure 28 vulcanizer. Metallic particles are stirred into theresincatalyst substances in sufficient quantity to be dispersedsubstantially uniformly throughout the mass. The mixture then is pouredinto a mold and cured in the manner prescribed for the particular resin.Polyurethane devices are made in the same way, but utilizing theappropriate resins and catalysts. The mold may be any desired shape toproduce a composite solid or foamed body composed of the elastomericmaterial and the metal particles, the latter being dispersed throughoutthe body, including its outer surfaces.

The metal particles should be formed of a metal that has excellentconductive propertiesand also should be one which, if it oxidizes, hasan electrically conductive oxide. Particles made from noble metals suchas silver and gold have the desired inherent conductivity and normallyform conductive oxides, but particles composed entirely of noble metalare quite expensive. It is preferred, therefore, to use discrete,spherical metal particles composed of base metals such as copper, ironand the like, coated with silver and which act very much like solidsilver particles, but which are less expensive. The size of theparticles may vary from 0.05 mil to 100 mils. Excellent results havebeen obtained utilizing particles in the 3-8 mils range. The size of theparticles should vary according to the thickness of the body or pad, theamount of force desired to be exerted on the body, and the value of thecurrent desired to be passed through the body. In general, the currentwhich can be accommodated by a body is directly proportional to the sizeof the metal particles.

A typical molded body may have its nonconductive portion formed ofsilicone resin and catalyst in the ratio of 10 to l by weight and itsconductive portion or portions formed of the same resin and catalyst, inthe same weight ratio, but having a particle to silicone ratio of 6 tol. The overall body may be of any desired area and of any desiredthickness, such as 0.10 inch. It should be apparent, however, that theratios and dimensions recited may be varied within. rather wide limitsdepending on the particular characteristics the resulting body are topossess. When a sample of the conductive portion of a typical body isviewed under a microscope, the silicone rubber appears to encapsulateeach metallic particle and isolate it from the others, but therubberdoes not prevent relative movement of the particles. When the body issubjected to compressive forces and deformed or compressed, the metallicparticles are forced to move relatively to one another and to theencapsulating rubber in such manner that a sufficient number of theparticles move into engagement with one another to establish aconductive train or path through the body portion. Current then may flowthrough the conductive body portion. The low shear resistance ofsilicone rubber and the nonadherence' of the rubber to the particlesfacilitate the movement of the particles. The resistance of theconductive body portion, when conductive, corresponds substantially tothe resistance of the metal particles. Since the electrical resistanceof noble metals, such as silver, is quite low, the resistance of theconductive portion also is quite low and, therefore, permits the latterto accommodate a high value current. For example, a conductive padconstructed of Dow Coming 3120 silicone rubber and containing 3 mil,silver coated copper particles in the ratio referred to above and havinga thickness of 0.06 inch was sandwiched between conventional terminalsand was capable of conducting a current of 50 amperes withoutimpairment. Another similar pad was incorporated in a l l5-volt ACcircuit including a 25-watt electric lamp bulb and was cycled at therate of cycles per minute. After more than 7 million cycles ofoperation, the pad still functioned perfectly.

[t is believed that when a conductive path is established through thepad the current density of such path between the other circuitcomponents is much less than that of the point to point contact ofconventional metal-to-metal connectors. The resistance of the bodyportion, when conductive, has been measured to be 0.0025 ohms which isequivalent to the resistance of 4.7 inches of 18 gauge wire or 3 inchesof 20 gauge wire.

When the compressive forceapplied to the pad is released, the inherentresilience of the silicone rubber causes the latter to expand and assumeits normal, un-

stressed condition, whereupon the engaged conductive particles areforced to move out of engagement, thereby dis-establishing or breakingthe conductive path. If there should be any arcing between particles asthey separate from one another, the arcing will be confined to theinterior of the body. Even though the presence of an arc may destroy orimpair the current conductive capacity of the particles between whichcurrent conductive capacity of the particles between which the arcforms, there are so many particles in the body and, consequently, somany possible current conductive paths that a potential path alwaysexists through the body throughout its life expectancy. The presence ofarcs within the body leaves a track, but because of the low carboncontent of the silicone rubber the arcing track is composed ofnonconductive inorganic matter, rather than a conductive carbon tracksuch as would be left in organic materials.

An occupant sensor seat switch indicated generally by reference numeral11 is adapted to sit in a pocket 12 in the seat foam 13 just below theseat covering of a conventional automobile seat 14.

According to the first embodiment, an occupant sensor seat switch 11comprises a body 15 formed of a resilient, electrically nonconductive,compressible material such as polyurethane foam. Resilient pads 16 and17 having electrically conductive particles 18 dispersed throughoutextend through the foam body 15. The resilient pads 16 and 17 areprovided so that they fit snugly in the holes of the foam body 15.Adhesively bonded to the bottom side of the polyurethane foam body 15 isa copper coated polyester film 19. The film 19 provides structuralsupport for the switch 11 and the copper coating 20 makes electricalcontact from pads 16 to pads 17. Two copper coated polyester films 21and 22 are adhesively bonded to the top of the polyurethane body 15.Copper coated film 21 electrically connects pads 16 together and coppercoated film 22 electrically connects pads 17 together. It is necessarythat films 21 and 22 be electrically isolated. It is necessary, however,that the adhesive does not contact the resilient pads 16 and 17. Aterminal 23 is riveted to the polyester film 20 so that an electricalconnection is made from wire 25 to the resilient pads 16 via the coppercoating on the polyester film 20. A similar connection is made to pads17 from wire 28 by terminal 26.

When the switch 11 is used in an automobile seat and an occupant sits inthat seat, pads 16 and 17 will be compressed rendering them conductive.A circuit will be completed through wire 25, terminal 23, the coppercoating on polyester film 20, the compressed conductive pads 16, coppercoating 20 on polyester film 19, compreessed conductive pads 17, thecopper coating on polyester film 21, terminal 26 to wire 28.

FIG. 6 represents an electrical schematic of the embodiment shown inFIGS. 2, 3, 7 and 8. In order for the switch 11 to be closed, it isnecessary that at least one of pads 16 and one of pads 17 be compressed.

Shown in FIGS. 9, l0 and 11 is a second embodiment. An occupant sensorseat switch 31 is comprised of a body 35 made from resilientnonconductive, compressible material such as polyurethane foam.Resilient pads 36 having electrically conductive particles dispersedthroughout as previously described fit snugly and extend through thefoam body. The foam body 35 is sandwiched between two copper coatedpolyester films 37 and 38 which are adhesively bonded to the foam body.A terminal 40 is riveted at 41 to the upper polyester film 37 such thatelectrical contact is made from wire 39 to the copper coating on thefilm 37. A similar terminal 43 makes contact from the wire 42 to thecopper coating on the bottom polyester film 38. When any one of theresilient pads 36 is compressed a circuit will be completed from thewire 39 to the copper coating on the upper polyester film 37 through thecompressed pad 36 to the copper coating on the bot- 6 tom polyester film38 to wire 42 as shown by the schematic in FIG. 11.

In making the switches 11 and 31 the bottom polyester film can be madethicker than the upper film so that the switch has some structuralrigidity. As a specific example in the embodiments shown in FIGS. 2, 3,7 and 8 the bottom polyester film can be 0.014 copper coated mylar andthe upper films 20 and 21 can be 0.005 copper coated mylar. In theembodiment shown in FIGS. 9 and 10v the bottom film 38 can be 0.014copper coated mylar and the top film 37 can be 0.005 copper coatedmylar.

Numerous changes and modifications can be made without departing fromthe true spirit of the invention. For example, the adhesive used to bondthe copper coated polyester film to the foam body may be replaced by anelectrically conductive adhesive. By doing this the copper coating onthe polyester film may be eliminated. Materials other than polyurethanemay be used to make the foam body. It is necessary, however, that thesematerials be compressible, resilient, and nonconductive. The number ofresilient pads employed may be varied also. According to the electricalschematic desired, the pads may be connected in series, parallel, orseries/parallel relationship or there may be just one pad.

We claim:

1. A flexible pressure sensitive switch for sensing the presence of anoccupant in a vehicle seat, said switch comprising:

first and second flexible, sheet-like, relatively strong laminates eachcomprising a film of insulation material having a thin conductivecoating on one side;

a fiat electrically nonconductive body of resilient compressible foamedmaterial interposed between said first and second laminates, the uppersurface of said body being adhesively bonded to the conductive coatingof said first laminate and the lower surface of said body beingadhesively bonded to the conductive coating of said second laminate,said body having a set of at least two longitudinally spaced openingseach extending from said upper surface to said lower surface, each ofsaid openings being open to the respective portions of said conductivecoatings overlying said openings;

a resilient compressible contact pad occupying each of said openings insaid body, each said contact pad being made of an elastomer withconductive particles dispersed therethrough such that said contact padis electrically conductive when compressed above a predetermined valueand electrically nonconductive when uncompressed, each said contact padhaving end portions facing the respective conductive coatings on saidlaminates for conductive connection therewith so that pressure appliedto a localized portion of said first laminate overlying said contact padwill result in compression of said contact pad between the respectiveconductive coatings of said laminates to provide a bridging conductivepath therebetween, said body normally maintaining said laminates in aspaced relation such that each said contact pad is maintained in asubstantially uncompressed condition in the absence of pressure applieddirectly against said localized portion of said first laminate overlyingsaid contact pad;

and menas for making external electrical connection to said conductivecoatings whereby the application of pressure against any of saidlocalized portions of said first laminate overlying said contact padscompletes a ciricuit to said external connection means. 2. The switchaccording to claim 1 wherein: said body has two sets of saidlongitudinally spaced openings, one of said sets of openings beinglaterally spaced from the other of said sets of openings, one each ofsaid openings being occupied by one of said contact pads; the conductivecoating of one of said laminates overlying the contact pads occupyingall of said openings and providing a conductive path interconnecting allof said contact pads, the conductive coating of the other of saidlaminates being in the form of two electrically isolated portions, oneof said isolated portions overlying the contact pads occupying said oneset of openings and the other of said isolated portions overlying thecontact pads occupying said other set of openings; said externalconnection means comprising terminal means connected to said isolatedportions of conductive coating of said other laminate wherebyapplication of pressure against the localized portions of said firstlaminate overlying at least one of the contact pads occupying saidsecond set of openings is required to complete a circuit to saidexternal connection means. I f 3. In combination, a vehicle seatincluding a pad of foam material having a recessed pocket in onelocalized area thereof, and a flexible pressure sensitive switchdisposed within said recessed pocket for sensing the presence of anoccupant on said one localized area of said seat pad, said switchcomprising:

first and second flexible, sheet-like, relatively strong laminates eachcomprising a film of insulation material having a thin conductivecoating on one side;

a flat electrically nonconductive body of resilient compressible foamedmaterial interposed between said first and second laminates, the uppersurface of said body being adhesively bonded to the conductive coatingof said first laminate and the lower surface of said body beingadhesively bonded to the conductive coating of said second laminate,said body having a set of at least two longitudinally spaced openingseach extending from said upper surface to said lower surface, each ofsaid openings being open to the respective portions of said conductivecoatings overlying said openings;

a resilient compressible contact pad occupying each of said openings insaid body, each said contact pad being made of an elastomer withconductive particles dispersed therethrough such that said contact padis electrically conductive when compressed above a predetermined valueand electrically nonconductive when uncompressed, each said contact padhaving end portions facing the respective conductive coatings on saidlaminates for conductive connection therewith so that during seatoccupancy pressure applied to a localized portion of said first laminateoverlying said contact pad will result in compression of said contactpad between the respective conductive coatings of said laminates toprovide a bridging conductive path therebetween; said body normallymaintaining said laminates in a spaced relation such that each saidcontact pad is maintained in a substantially uncompressed condition inthe absence of pressure applied directly against said localized portionof said first laminate overlying said contact pad;

and means for making external electrical connections to said conductivecoatings whereby during occupancy of said seat at said one localizedarea of said seat pad the application of pressure against any of saidlocalized portions of said first laminate overlying said contact padscompletes a circuit to said external connection means. l

4. The combination of a vehicle seat and a switch assembly according toclaim 3 wherein:

said body has two sets of said longitudinally spaced openings, one ofsaid sets of openings being laterally spaced from the other of said setsof openings, one each of said openings being occupied by one of saidcontact pads;

the conductive coating of one of said laminates overlying the contactpads occupying all of said openings and providing a conductive pathinterconnecting all of said contact pads, the conductive coating of theother of said laminates being in the form of two electrically isolatedportions, one of said isolated portions overlying the contact padsoccupying said one set of openings and the other of said isolatedportions overlying the contact pads occupying said other set ofopenings;

saidexternal connection means comprising terminal means connected tosaid isolated portions of the conductive coating of said other laminatewhereby application of pressure against the localized portions of saidfirst laminate overlying at least one of the contact pads occupying saidfirst set of openings and at least one of the contact pads occupyingsaid second set of openings is required to complete a circuit to saidexternal connection means.

1. A flexible pressure sensitive switch for sensing the presence of anoccupant in a vehicle seat, said switch comprising: first and secondflexible, sheet-like, relatively strong laminates each comprising a filmof insulation material having a thin conductive coating on one side; aflat electrically nonconductive body of resilient compressible foamedmaterial interposed between said first and second laminates, the uppersurface of said body being adhesively bonded to the conductive coatingof said first laminate and the lower surface of said body beingadhesively bonded to the conductive coating of said second laminate,said body having a set of at least two longitudinally spaced openingseach extending from said upper surface to said lower surface, each ofsaid openings being open to the respective portions of said conductivecoatings overlying said openings; a resilient compressible contact padoccupying each of said openings in said body, each said contact padbeing made of an elastomer with conductive particles dispersedtherethrough such that said contact pad is electrically conductive whencompressed above a predetermined value and electrically nonconductivewhen uncompressed, each said contact pad having end portions facing therespective conductive coatings on said laminates for conductiveconnection therewith so that pressure applied to a localized portion ofsaid first laminate overlying said contact pad will result incompression of said contact pad between the respective conductivecoatings of said laminates to provide a bridging conductive paththerebetween, said body normally maintaining said laminates in a spacedrelation such that each said contact pad is maintained in asubstantially uncompressed condition in the absence of pressure applieddirectly against said localized portion of said first laminate overlyingsaid contact pad; and means for making external elelctrical connectionto said conductive coatings whereby the application of pressure againstany of said localized portions of said first laminate overlying saidcontact pads completes a ciricuit to said external connection means. 2.The switch according to claim 1 wherein: said body has two sets of saidlongitudinally spaced openings, one of said sets of openings beinglaterally spaced from the other of said sets of openings, one each ofsaid openings being occupied by one of said contact pads; the conductivecoating of one of said laminates overlying the contact pads occupyingall of said openings and providing a conductive path interconnecting allof said contact pads, the conductive coating of the other of saidlaminates being in the form of two electrically isolated portions, oneof said isolated portions overlying the contact pads occupying said oneset of openings and the other of said isolated portions overlying thecontact pads occupying said other set of openings; said externalconnection means comprising terminal means connected to said isolatedportions of conductive coating of said other laminate wherebyapplication of pressure against the localized portions of said firstlaminate overlying at least one of the contact pads occupying saidsecond set of openings is required to complete a circuit to saidexternal connection means.
 3. In combination, a vehicle seat including apad of foam material having a recessed pocket in one localized areathereof, and a flexible pressure sensitive switch disposed within saidrecessed pocket for sensing the presence of an occupant on said onelocalized area of said seat pad, said switch comprising: first andsecond flexible, sheet-like, relatively strong laminates each comprisinga film of insulation material having a thin conductive coating on oneside; a flat electrically nonconductive body of resilient compressiblefoamed material interposed between said first and second laminates, theupper surface of said body being adhesively bonded to the conductivecoating of said first laminate and the lower Surface of said body beingadhesively bonded to the conductive coating of said second laminate,said body having a set of at least two longitudinally spaced openingseach extending from said upper surface to said lower surface, each ofsaid openings being open to the respective portions of said conductivecoatings overlying said openings; a resilient compressible contact padoccupying each of said openings in said body, each said contact padbeing made of an elastomer with conductive particles dispersedtherethrough such that said contact pad is electrically conductive whencompressed above a predetermined value and electrically nonconductivewhen uncompressed, each said contact pad having end portions facing therespective conductive coatings on said laminates for conductiveconnection therewith so that during seat occupancy pressure applied to alocalized portion of said first laminate overlying said contact pad willresult in compression of said contact pad between the respectiveconductive coatings of said laminates to provide a bridging conductivepath therebetween; said body normally maintaining said laminates in aspaced relation such that each said contact pad is maintained in asubstantially uncompressed condition in the absence of pressure applieddirectly against said localized portion of said first laminate overlyingsaid contact pad; and means for making external electrical connectionsto said conductive coatings whereby during occupancy of said seat atsaid one localized area of said seat pad the application of pressureagainst any of said localized portions of said first laminate overlyingsaid contact pads completes a circuit to said external connection means.4. The combination of a vehicle seat and a switch assembly according toclaim 3 wherein: said body has two sets of said longitudinally spacedopenings, one of said sets of openings being laterally spaced from theother of said sets of openings, one each of said openings being occupiedby one of said contact pads; the conductive coating of one of saidlaminates overlying the contact pads occupying all of said openings andproviding a conductive path interconnecting all of said contact pads,the conductive coating of the other of said laminates being in the formof two electrically isolated portions, one of said isolated portionsoverlying the contact pads occupying said one set of openings and theother of said isolated portions overlying the contact pads occupyingsaid other set of openings; said external connection means comprisingterminal means connected to said isolated portions of the conductivecoating of said other laminate whereby application of pressure againstthe localized portions of said first laminate overlying at least one ofthe contact pads occupying said first set of openings and at least oneof the contact pads occupying said second set of openings is required tocomplete a circuit to said external connection means.